Answer to Question #158877 in Genetics for Arjan judge

Question

Which of the following answers contributes to genetic diversity within a species

mutation occurs in DNA sequence, when individual undergoes asexual reproduction, when sexual reproduction occurs between 2 individuals

Answer 1

Which of the following answers contributes to genetic diversity within a species?

1. Mutation occurs in DNA sequence
2. When individual undergoes asexual reproduction
3. When sexual reproduction occurs between 2 individuals

Solution:

1. Mutations in DNA sequence can occur in somatic cells (any body cells except sex cells, which fuse to create a zygote), progenitor cells of gametes, and gametes (sex cells). If the mutation occurs in somatic cells (except progenitor cells of gametes), it can't be passed to offspring so it can`t contribute to genetic diversity within species. But if the mutation occurs in progenitor cells of gametes or gametes, gametes would keep the mutation and pass it to the zygote. The organism developed from this zygote would have a new feature that is absent in its parents. So in some conditions mutation in DNA sequence can contribute to genetic diversity. But not in all conditions and we need to choose only one variant so we won`t consider it.
2. During asexual reproduction, the new individual develops from the somatic cells of the parent organism. The mutations occur in somatic cells every time DNA replicates so somatic cells even within the same organism have slightly diverse genotypes. That means that the daughter organism anyway would differ from the parent organism. But the contribution of that phenomenon to the genetic diversity within species is so insignificant comparing to the contribution of sexual reproduction so we better neglect it.
3. Sexual reproduction between two individuals suggests the fusion of their haploid gametes to form a diploid zygote. The type of cell division (meiosis) allows achieving the maximal diversity of gametes genotypes. Meiosis includes two processes that contribute to gametes diversity: crossing over (the swap of genetic material between paired chromosomes) and random chromosome separation between cells. The diversity of daughter organisms also increase because of the fusion of the random gametes.

Answer:

Sexual reproduction between 2 individuals contributes to genetic diversity within a species.